public void TestDay12Part1()
        {
            var moon1 = new Moon {
                Name = "Io", X = -10, Y = -13, Z = 7
            };
            var moon2 = new Moon {
                Name = "Europa", X = 1, Y = 2, Z = 1
            };
            var moon3 = new Moon {
                Name = "Ganymede", X = -15, Y = -3, Z = 13
            };
            var moon4 = new Moon {
                Name = "Callisto", X = 3, Y = 7, Z = -4
            };

            var system = new MoonSystem();

            system.AddMoon(moon1);
            system.AddMoon(moon2);
            system.AddMoon(moon3);
            system.AddMoon(moon4);

            var output = system.CalculateTotalEnergy(1000);

            Assert.AreEqual(8454, output);
        }
        public void SetUp()
        {
            var moon1 = new Moon {
                Name = "Io", X = -1, Y = 0, Z = 2
            };
            var moon2 = new Moon {
                Name = "Europa", X = 2, Y = -10, Z = -7
            };
            var moon3 = new Moon {
                Name = "Ganymede", X = 4, Y = -8, Z = 8
            };
            var moon4 = new Moon {
                Name = "Callisto", X = 3, Y = 5, Z = -1
            };

            _system = new MoonSystem();
            _system.AddMoon(moon1);
            _system.AddMoon(moon2);
            _system.AddMoon(moon3);
            _system.AddMoon(moon4);
        }